A brake motor of this type is, for example, known in the prior art from the document EP-A-0,249,522, and is particularly illustrated by FIG. 4 of this document.
Moreover, document FR-A-2 638 214 discloses a brake motor comprising: an essentially cylindrical body filled with a hydraulic fluid subjected to a variable pressure; a mechanical actuator comprising a control member which can be accessed from outside this body; a brake piston shutting off the body in leaktight fashion and capable of sliding therein under the effect of the actuator in order to actuate, in turn, at least one friction member; and an automatic adjustment device arranged inside the body between the mechanical actuator and the piston in order to take up the play resulting from the wear of the friction member, this device itself comprising a selectively rotatable nut in which a rotationally fixed screw is engaged, one end of the screw being capable of receiving a thrust from the mechanical actuator, and the other end of the screw passing through the piston in leaktight fashion in order to be subjected to atmospheric pressure, one end of the nut having a tapered shoulder capable of being selectively rotationally blocked by an internal tapered surface of the piston, rotationally fixed, against which this shoulder is pressed with a force which increases with the pressure of the hydraulic fluid, the mechanical actuator being of the type of actuators which comprise two plates capable of relative rotation, one plate being securely fastened to one end of the screw, and the other plate being fastened to a spindle passing through the body in leaktight fashion.
The design of brake motors, regardless of their structure, their bulk and their functional specifications, permanently seeks to reduce the number of components, simplify the manufacture, reduce the bulk and increase, if still possible, the reliability of these devices, which are mass produced.